AES E-Library

A New Surround-Stereo-Surround Coding Technique

A new technique is described in which a stereo signal (two-channel) is derived from a multichannel surround-sound signal without the original multichannel information being lost. There are no restrictions on the way in which the down mix to two channels takes place. An extra code is generated which contains the information required for the expansion to the multichannel version, and this code is added inaudibly to the down-mixed signal. An inaudible addition is possible because of the masking properties of human hearing. By retrieving from the stereo signal the information added, it is possible to produce again the original multichannel surround-sound sensation. The technique is very suitable for application in HDTV: a surround-sound signal can be down-mixed to a compatible stereo signal. Because of the compatibility, stereo reception is possible. By equipping the receiver with additional electronics, however the surround-sound signal can also be decoded from this stereo signal. Multichannel surround-sound reception is thus obtained over a two-channel transmission path.